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Flow Statistics used to Develop Building Blocks Recommendations for Big Cypress. Indicators of Hydrologic Alteration – Environmental Flow Component (EFC) Appendix D 2 and 10 year recurrence interval flows Appendix E. Indicators of Hydrologic Alteration – Environmental Flow Component (EFC).
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Flow Statistics used to Develop Building Blocks Recommendations for Big Cypress • Indicators of Hydrologic Alteration – Environmental Flow Component (EFC) Appendix D • 2 and 10 year recurrence interval flows Appendix E
Indicators of Hydrologic Alteration – Environmental Flow Component (EFC) • Divides the hydrograph into high flow (>75th percentile) and low flow (<50th percentile) • High flows are further divided into Large Floods (10 year recurrence), Small Floods (2 year recurrence) and High Flow Pulses (rise faster than 25% and fall faster than 10%) • Low flows also include Extreme Low Flows (<10th percentile) • Percentile statistics of the low flows for each month are also generated
2 – year recurrence interval (1.5 - 4 year) • Bank Full Flow – Flushing accumulated fine sediments from gravel, scouring pools, building riffles, removing vegetation from active channel inundating bars and maintaining channel capacity. • Effective Discharge – Flow that transports the largest amount of sediment when averaged over time.
High Flow Calculations • IHA calculates high flow stats based on daily average flows, by default the 2 year and 10 year recurrence intervals. • PeakFQ – USGS program to Flood Frequency using log-pearson Type III regression based on instantaneous annual peaks